A typical cellular communication system includes one or more wireless base stations and multiple wireless mobile stations, as shown in FIG. 1A. Each base station (BS) defines a cell of coverage, where each mobile station (MS) can communicate with a BS via a BS→MS link while within communication range of the BS cell coverage. In many cellular systems, radio resource management (RRM) for orthogonal frequency division multiple access (OFDMA)-based cellular systems is utilized. Such systems address resource allocations (e.g., frequency, time, power), among BS→MS links (i.e., transmission channels defined by frequency carriers, spreading codes or time slots).
In a Relay Enhanced Cellular (REC) system, wireless relay stations (RSs) are deployed to improve wireless (e.g., radio frequency) link quality and/or extend cell coverage. For example, RSs have been used for improving throughput, coverage, and spectrum efficiency of cellular systems. FIG. 1B shows an example cellular system including a base station BS and multiple mobile stations (MSs) and relay stations (RS1, . . . , RS6). A two-hop transmission takes place between a BS and MS via a RS, wherein a RS may be an MS itself. The introduction of relay stations brings forth new challenges to the RRM design. RRM for relay enhanced cellular (REC) systems has to address resource allocations among BS→MS, BS→RS, and RS→MS communication links.
The IEEE P802.16j (IEEE 80216j) relay network standard defines two types of relay stations (or relay modes of operation): Transparent and non-transparent. FIG. 2A shows IEEE P802.16j communication time frame structures for a transparent relay station (transparent RS), as described in “IEEE 802.16J Relay-Based Wireless Access Networks: An Overview”, Vasken Genc, Sean Murphy, Yang Yu, and John Murphy, University College Dublin, School Of Computer Science And Informatics, IEEE Wireless Communications, October 2008. FIG. 2B shows said time frame structure wherein a transparent RS serves those MSs that can decode the control information from the BS. A transparent RS need not transmit control information itself. A benefit of relaying with a transparent RS is capacity enhancement for the REC system.
FIG. 3A shows a IEEE P802.16j communication time frame structure for a non-transparent relay station (non-transparent RS), as described in “IEEE 802.16J Relay-Based Wireless Access Networks: An Overview”, Vasken Genc, Sean Murphy, Yang Yu, and John Murphy, University College Dublin, School Of Computer Science And Informatics, IEEE Wireless Communications, October 2008. FIG. 3B shows said time frame structure, wherein a non-transparent RS serves mobile stations that cannot decode the control information from the BS. The non-transparent RS must transmit control information at the beginning of the communication time frame. Each MS will have an implicit “understanding” that the non-transparent RS is actually a base station. A benefit of relaying with a non-transparent RS is coverage extension for the REC system.